Rare silver cased SLIDE RULE calculator pocket watch c1890

This is a rare example of a pocket watch with a slide rule function.

These were made in 1880, by Charles Meyrat and Rodolphe Perdrizet who patented the combination of slide rule and pocket watch. The site of production of these watches was Alphonse Beaudroit’s small factory in Seloncourt

Around 500 of these watches were made and this is 56 of the 500

This is particularly scarce as it comes in a silver case and the majority are in white metal cases

Movement – the gilt bridge movement has a cylinder escapement and is in  99% mint condition – flawless.

The movement is protected by a snap on silver bezel with a glass panel and decorated with bright cut engraving

Case – the movement comes in a silver open face case, which has a hinged back and bezel. The case is decorated with engine turning and a smooth plain finish on the sides

The case has two knobs these control the slide rule function on the dial – see below.

The case is in 95% mint condition – superb condition showing very little wear

Dial – the white enamel dial has a pair of gilt hand is in 100% mint condition

Surrounding the dial are two silver chapter rings and a blue steel pointer. The inner chapter ring and the pointer are moved by the two knobs on the side of the case. These dials are for the slide rule function and are in 100% mint condition

The watch measures 59mm wide x 21mm deep

The watch is stem wound / pin set

The watch has a thick bevelled mineral glass